[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: XML Schema becomes a W3C Recommendation
Rick Jelliffe wrote: > > From: Eric van der Vlist <vdv@d...> > > >RSS 1.0 can't be described by W3C XML Schema (nor by a DTD). > > >A W3C XML Schema on RSS 1.0 would have been incompatible with 2 of our > >requirements: > > >1) Simplicity: W3C XML Schema would have imposed an order on elements. > >2) Modularity: you can't say that you want to allow any element from any > >namespace from undeclared modules with W3C XML Schema. > > This brings up the old question of whether a schema defines or models (the > "document type declaration" versus "document type definitions" issue.) If we > say that the schema models the requirement (i.e., there may be some > constraints which are not checked) then an XS schema certainly can made for > RSS. Exactly. We have taken the opposite approach where we believe that our requirement must constrain the schema languages we will use. Also it's not only a matter of constraints not being checked, but of non constraints on element order being imposed. > It is like the early claim that a DTD could not be made for RDF. However, a > DTD fragment certainly could, and the ANY declared content type model some > elements nicely. No! I can use a xsd:any to specify that I want any namespace except the target namespace, but here we need to exclude all namespaces of the approved modules and that's not possible with W3C XML Schema. > I am not up-to-date with RSS recently: can RELAX and TREX cope with its > model OK? I believe Schematron can. Yes, it should be possible to define RELAX, TREX, Schematron and examplotron schemas for RSS. Eric > Cheers > Rick Jelliffe > > ------------------------------------------------------------------ > The xml-dev list is sponsored by XML.org, an initiative of OASIS > <http://www.oasis-open.org> > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > To unsubscribe from this elist send a message with the single word > "unsubscribe" in the body to: xml-dev-request@l... -- See you in Hong Kong for www10: http://www.www10.org/program/w10-half-tut.shtml#ta5 ------------------------------------------------------------------------ Eric van der Vlist http://xmlfr.org http://dyomedea.com http://xsltunit.org http://4xt.org http://examplotron.org ------------------------------------------------------------------------
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